Primary Pad -- allows multiple users to create a document together and chat about it as they work. also, TitanPad. Also Crocodocs.

WikiSpaces -- Create a multi-paged "site"; easy to embed videos, images and links. No chatting feature

Google Doc -- Collaborate to create a page; allows for chatting and video chatting (how to do this)

TodaysMeet: Create your own internet chat room; great for brainstorming with others and for discussing projects-in-process

Jeff Utrecht's article on collaborative tools, "What's Your Container?" A great introduction to thinking about working collaboratively.

Ning-like social network sites (now that Ning is no longer free)

One Free Social Networking site I really like--Wall.FM